The inventive concept relates generally to nonvolatile memory devices, and more particularly, three-dimensional (3D) nonvolatile memory devices having a split ground selection line structure.
Semiconductor memory devices can be roughly divided into two categories according to whether they retain stored data when disconnected from power. These categories include nonvolatile memory devices, which retain stored data when disconnected from power, and volatile memory devices, which lose stored data when disconnected from power.
Nonvolatile memory devices, such as flash memory, have gained increasing popularity in recent years due to the proliferation of devices requiring large amounts of nonvolatile data storage. Examples of such devices include computers, mobile phones, smart phones, personal digital assistants (PDAs), handheld PCs, gaming machines, fax machines, scanners, and printers, to name but a few.
In an effort to improve the integration density of nonvolatile memory devices such as flash memory devices, researchers have developed techniques for forming nonvolatile memory cells in 3D arrays. An example of a device comprising such a 3D array is a so-called vertical NAND flash memory, or 3D flash memory device. In a typical vertical NAND flash memory, word lines are stacked in a vertical direction to a substrate, and cell strings are configured by forming pillars which penetrate the stacked word lines.
To reduce loading of the word lines in a vertical NAND flash memory device, a ground selection line (GSL) split scheme is used. In a device using the split GSL scheme, GSL lines may be controlled for multiple units in a single memory block. Accordingly, through this structure, operation performance can be improved by reducing loading occurring according to relatively large word line capacity.